Aircraft today are an indispensable part of a globally functioning transport system. No other mode of transportation in recent years has achieved such high growth rates in transporting capacities as the aircraft. The advantages of this mode of transportation are its speed, safety, and reliability.
In addition to the transporting of passengers, the transporting of goods, the so-called airfreight, is increasingly gaining in importance. The term airfreight covers all goods which can be transported by means of the aircraft mode of transportation, which may include live goods (such as animals, but not persons). Cargo aircraft or passenger aircraft are provided for transporting these goods. Passenger aircraft typically have a cargo hold for example beneath the passenger deck. In contrast, cargo aircraft are provided exclusively for the transporting of airfreight and therefore do not have passenger seats (except for so-called courier seats), but only have a transporting system for corresponding airfreight containers.
In addition to the aforementioned advantages of the aircraft mode of transportation, especially also with regard to the transporting of airfreight, air transportation also has some known disadvantages. In particular, airfreighting is more expensive than surface transporting or transporting by sea. For another thing, an aircraft also has higher fuel consumption. For this reason, there has always existed the requirement of a utilization which is as effective as possible of the cargo hold which is available in the aircraft.
Airfreight containers (or so-called Unit Load Devices (ULDs)) are standardized containers which are specifically provided for the transporting of airfreight and are used to transport luggage, freight, mail, etc. in the cargo hold of corresponding cargo aircraft. These airfreight containers enable large volumes of transported cargo to be bundled into comparatively large units, which altogether shortens the loading operation of the aircraft. Such airfreight containers are typically standardized for use for the different aircraft types, the body cross sections of which can differ from each other. Such airfreight containers are closed containers consisting of aluminium or a combination of aluminium (frames) and plastic (walls, roofs). These airfreight containers, depending upon the type of freight which is located therein, can also have built-in refrigerating units (see FR 2 726 255 A1). In addition, airfreight containers are known which transport the freight in an explosion-safe manner (see EP 617 687 B1).
Aircraft of today operate at flying altitudes at which the temperature lies way below 0° C. and at which the air pressure is extremely low. In order to now create an environment for the protection of some of the goods which are to be transported, such as live animals, which is at least comparable with the environment which prevails on the ground, aircraft of today have supply systems in their cargo hold which serve especially for air conditioning and for pressurization of the cargo hold with compressed air.
The fact that these supply systems and especially the air conditioning and pressuring of the cargo hold significantly limit the design of the body cross section and, moreover, bring with them a weight which is not to be neglected, is problematical. In particular, the aircraft has to have a so-called pressurized body which is designed specifically for pressurizing, for which the body of the aircraft has to be designed in an essentially round or at least oval form. As a result of this, the geometry of a corresponding airfreight container must typically also be orientated towards this body geometry.
In addition to this, many of these supply systems, and especially the compressed air supply system and air conditioning system are always carried along even if these are not at all necessary for much of the transported goods. These supply systems involve an additional weight on the one hand, and on the other hand create additional operating and maintenance costs.
Airfreight containers which are used today furthermore create a relatively high logistical cost if they are not stored in the cargo hold of the aircraft but on the ground or in a warehouse. Above all, for airfreight containers which have to be supplied with a medium, for example with compressed air, oxygen, water, refrigerated or temperature-conditioned air, etc., the corresponding supply chain must not be broken, or at least only briefly broken, for which airfreight containers which are known today are not designed, or designed only with limitations. As already previously mentioned, airfreight containers with an integrated refrigerating unit do indeed exist. However, these airfreight containers are not autonomous since these are still based on a pressurized (that is to say pressurized with compressed air) cargo hold of the aircraft and since, on the other hand, an air conditioning system which is already provided by the aircraft cannot be completely dispensed with in this case. Moreover, an airfreight container with an integrated refrigerating unit typically obtains its power via the aircraft and therefore is not autonomous either to that effect.